@sap/eslint-plugin-cds/lib/rules/js/no-shared-handler-variable.js

ESLint plugin including recommended SAP Cloud Application Programming model and environment rules

/*
Use cases not yet covered:

//---------
INLINE EXTENSION
class FooService extends require('@sap/cds').ApplicationService { ... }

//---------
REFERENCED FUNCTION
function bad() { ... }

class ... {
    this.on('', bad)
}

//---------
METHOD
class ... {
    bad () {}

    this.on('', this.bad)
}

//---------
IMPORTED FUNCTION
const { bad } = require('./bad')

class ... {
    this.on('', bad)
}

//---------
NON-CLASS-BASED CDS SERVICE
cds.services['myService'].on('READ', 'Books', () => {})
*/

'use strict'

const { RULE_CATEGORIES } = require('../../constants')
const { CdsHandlerRule } = require('./CdsHandlerRule')

class NoSharedVariable extends CdsHandlerRule {
  AssignmentExpression(node) {
    if (!this.isInsideCapHandlerRegistration) return
    const declaringScope = this.findDefinitionScope(node.left.name)
    if (declaringScope?.isLocal === false) {
      this.context.report({
        node,
        messageId: 'noSharedHandlerVariable',
        data: {
          definitionScope: declaringScope.scope.name
        }
      })
    }
  }
}

module.exports = {
  meta: {
    type: 'problem',
    docs: {
      recommended: true,
      category: RULE_CATEGORIES.javascript,
      description: 'Enforce that variables can not be used to share state between handlers.'
    },
    schema: [],
    messages: {
      noSharedHandlerVariable: 'Assignment to a non-local variable inside a CDS event handler (was declared in scope "{{definitionScope}}").'
    },
    hasSuggestions: true
  },
  create: context => new NoSharedVariable(context).asESLintVisitor()
}